As is known, currently marketed front-loading home laundry washing machines generally comprise: a substantially parallelepiped-shaped outer boxlike casing structured for resting on the floor; a substantially bell-shaped washing tub which is suspended in floating manner inside the casing, directly facing a laundry loading/unloading through opening realized in the front wall of the casing; a substantially cylindrical elastically-deformable bellows, which connects the front opening of the washing tub to a laundry loading/unloading opening formed in the front wall of the casing; a porthole door which is hinged to the front wall of the casing to rotate to and from a closing position in which the door closes the laundry loading/unloading opening in the front wall of the casing for watertight sealing the washing tub; a substantially cylindrical, bell-shaped revolving drum structured for housing the laundry to be washed, and which is arranged inside the washing tub with its concavity facing the laundry loading/unloading opening and is supported in axially rotating manner so as to be able to freely rotate about its substantially horizontally-oriented longitudinal axis; and finally an electrically-powered motor assembly which is structured for driving into rotation the revolving drum about its longitudinal axis inside the washing tub.
Like other home laundry washing machines, this type of laundry washing machine is furthermore provided with a detergent dispensing assembly which is generally located inside the boxlike casing, immediately above the washing tub, and is structured for selectively feeding into the washing tub, according to the washing cycle manually-selected by the user via a control panel generally located on the front wall of the boxlike casing, a given amount of detergent, softener and/or other washing agent suitably mixed with fresh water arriving from the water mains; and with a fresh-water supply circuit structured for selectively drawing fresh water from the water mains according to the washing cycle manually-selected by the user, and channeling said water into the detergent dispensing assembly or directly into the washing tub.
The detergent dispensing assembly, in turn, generally comprises a detergent drawer which is usually divided into a number of detergent compartments each structured for being manually fillable with a corresponding detergent product, and which is fitted/inserted in manually extractable manner into a completely recessed drawer housing whose entrance is located on front wall of the boxlike casing, above the porthole door, and whose bottom wall directly communicates with the inside of the washing tub via a connecting duct.
The fresh-water supply circuit is structured for drawing fresh water from the water mains and selectively and alternatively channeling said water into any one of the detergent compartments of the detergent drawer, so as to selectively flush the detergent, softener or other washing agent out of the compartment and down on the bottom of the drawer housing, and afterwards sweep the detergent, softener or other washing agent away from the bottom of the drawer housing directly into the washing tub.
As is known the hardness of the fresh water used for washing deeply negatively influences the cleaning efficiency of the detergents and softeners used in the washing cycle, thus the user is usually requested to considerably increase, when the hardness degree of the tap water is too high, the amount of detergent and softener used in the washing cycle and/or to mix the detergent with a given amount of very expensive, generally polycarboxylates-based, water-softening chemical product.
To solve this problem the European patent application No. 1085118 discloses a front-loading home laundry washing machine provided with an internal water softening device capable of reducing, during each washing cycle, the hardness degree of the tap water used in the pre-washing and washing phases of the washing cycle. This water softening device uses ion-exchange resins to restrain calcium and magnesium ions (Ca++ and Mg++) dissolved in the fresh water channeled to the washing tub, and uses brine (i.e. salt water) to periodically regenerate these ion-exchange resins. Salt water, in fact, is able to remove from the ion-exchange resins the calcium and magnesium ions previously combined/fixed to said resins.
Integration of the salt reservoir on the back of the detergent drawer has brought to a very complicated detergent-dispenser structure with a consequent significant increase in the detergent dispenser overall production cost.
Moreover the brine accidentally coming out of the salt reservoir accumulates on the bottom of the drawer housing which is in direct communication with the upper portion of the washing tub, thus the brine can reach quite easily the outer surface of the revolving drum with all problems concerned. The revolving drum, in fact, is generally made of metal material and gets rusty very quickly in presence of brine.
Last but not less important, the capacity of the salt reservoir on the back of the detergent drawer is too limited for the everyday-use typical of a traditional home laundry washing machine. It is unacceptable for a normal user to refill the salt reservoir every 3-4 washing cycles.
An aim of the present invention is therefore to realize an internal water softening device designed to eliminate the drawbacks referred above.